Polyamide resin composition and molded article

ABSTRACT

[Object] 
     It is intended to obtain a polyamide resin composition that is excellent in heat aging resistance and exhibits suppressed metal corrosive properties and copper-depositing properties. 
     [Means of solving the problems] 
     A polyamide resin composition comprising a polyamide resin (A), a copper compound (B), a bromide of an alkali metal and/or a bromide of an alkaline earth metal (C), and at least one phosphorus compound (D) selected from the group consisting of phosphite compounds represented by the following general formula (1), and phosphonite compounds represented by the following general formula (2): 
       phosphite compound: (RO) m P(OH) 3-m   (1) and
 
       phosphonite compound: (RO) n O(OH) 2-n (R)  (2)
         wherein m represents 1, 2, or 3; n represents 1 or 2; R represents an alkyl group, a phenyl group, or a partially substituted alkyl group or phenyl group; and if each of m and n is 2 or more, a plurality of (RO) groups in the general formulas (1) and (2) are the same or different from each other.

TECHNICAL FIELD

The present invention relates to a polyamide resin composition and amolded article.

DESCRIPTION OF THE RELATED ART

Polyamide resins have high mechanical properties (such as mechanicalstrength, rigidity, and impact resistance, etc.), toughness, heatresistance, and chemical resistance. The polyamide resins have been usedin various industrial fields such as clothing, industrial materials,automobiles, electric and electronic industries and other industrialfields.

In particular, the polyamide resins have higher heat aging resistancethan that of other resins. The polyamide resins are therefore suitablyused as materials for parts which receive a significantly large amountof heat, such as parts for engine compartments of vehicles.

The environmental temperatures inside the engine compartments ofvehicles have been increased recently in connection with higher densityof parts for engine compartments of vehicles and higher outputs ofengines. For this reason, a polyamide resin which can maintainsignificantly higher heat aging resistance for a longer period of timethan those of the traditional polyamide resins has been required.

One of the traditional techniques of enhancing the heat aging resistanceof the polyamide resins is addition of a copper compound (oxide or saltof copper) and a halogen compound.

Among the halogen compounds, an iodine compound is generally added. Atechnique of compounding a polyamide resin, a copper compound, an iodinecompound, and an aliphatic carboxylic derivative is known (for example,see patent literature 1).

However, iodine as a resource is mined from the ground, and itsefficient mining areas are limited. For this reason, the price of iodinecompounds has been rising in recent years. Thus, use of iodine compoundsin polyamide resins has a problem of increased production cost.

In contrast, bromine as a resource can be extracted from sea water orthe like, and is more inexpensive and industrially useful than iodine.Other techniques of adding a bromine compound rather than an iodinecompound have been developed to enhance the heat aging resistance of thepolyamide resin (for example, see patent literature 2 and 3).

CITATION LIST Patent Literature

-   [Patent literature 1] Japanese Patent Laid-Open No. 7-18176-   [Patent literature 2] International publication (WO) No. 2013-143858-   [Patent literature 3] National Publication of International Patent    Application No. 2011-511097

SUMMARY OF THE INVENTION Technical Problem

Bromine compounds, however, are more likely to cause metal corrosionthan iodine compounds. Furthermore, if polyamide resin compositionscontaining a bromine compound are used as materials for parts for enginecompartments of vehicles and the like, there is a concern that thebromine compound may corrode metallic parts of processing machines suchas extruders and molding machines. For example, conditions under whichsuch a polyamide composition containing a bromine compound should beconsidered. Accordingly, the development of a polyamide resincomposition which causes less corrosion of metal than before has beenrequired.

An object of the present invention is to provide a polyamide resincomposition which has high heat aging resistance, and is less likely tocause corrosion of metal and deposition of copper.

Solution to Problem

The present inventors, who have conducted extensive research to solvethe problems, have found that the problems can be solved by a polyamideresin composition comprising a polyamide resin, a copper compound, aspecified bromide, and a specified phosphorus compound.

Specifically, the present invention is as follows:

[1]

A polyamide resin composition comprising

a polyamide resin (A),

a copper compound (B),

a bromide of an alkali metal and/or a bromide of an alkaline earth metal(C), and

at least one phosphorus compound (D) selected from the group consistingof phosphite compounds represented by the following general formula (1)and phosphonite compounds represented by the following general formula(2):

phosphite compound: (RO)_(m)P(OH)_(3-m)  general formula (1) and

phosphonite compound: (RO)_(n)P(OH)_(2-n)(R)  general formula (2)

wherein m represents 1, 2, or 3; n represents 1 or 2; R represents analiphatic group, an aromatic group, or a partially substituted aliphaticgroup or aromatic group; and if each of m and n is 2 or more, aplurality of (RO) groups in the general formulas (1) and (2) are thesame or different from each other.[2]

The polyamide resin composition according to [1], wherein the coppercompound (B) is a copper halide compound.

[3]

The polyamide resin composition according to [1] or [2], wherein a molarratio of a halogen element/a copper element, in the polyamide resincomposition is 2/1 to 50/1.

[4]

The polyamide resin composition according to any one of [1] to [3],further comprising at least one fatty acid compound (E) selected fromthe group consisting of fatty acid esters, fatty acid amides, and fattyacid metal salts.

[5]

The polyamide resin composition according to [4], wherein the fatty acidcompound (E) has an acid value of 10 mg/g or less.

[6]

The polyamide resin composition according to [4] or [5], wherein thefatty acid compound (E) is a higher fatty acid metal salt with a metalcontent of 3.5 to 11.5% by mass.

[7]

The polyamide resin composition according to any one of [1] to [6],wherein the content of the copper element in the polyamide resincomposition is 0.005% by mass or more with respect to the total mass ofthe polyamide resin composition.

[8]

The polyamide resin composition according to any one of [1] to [7],wherein the mass ratio [x/y] of the bromide of an alkali metal and/orbromide of an alkaline earth metal (C) [x] to the phosphorus compound(D) [y] is 100/1 to 1/100.

[9]

The polyamide resin composition according to any one of [1] to [8],further comprising an inorganic filler (F).

[10]

The polyamide resin composition according to any one of [1] to [9],wherein a copper element is not deposited on the surface of a rolledsteel (SS400) after the polyamide resin composition is in contact withthe rolled steel at a temperature 30° C. higher than the melting pointof the polyamide resin (A) for 12 hours.

[11]

A molded article comprising a polyamide resin composition according toany one of [1] to [10].

[12]

The molded article according to [11], wherein the molded article is avehicle part.

Advantageous Effect of the Invention

According to the present invention, a polyamide resin composition thatis high heat aging resistance and exhibits suppressed metal corrosiveproperties and copper-depositing properties can be obtained.

EMBODIMENTS OF THE INVENTION

Hereinafter, an embodiment for carrying out the present invention(hereinafter, referred to as the “present embodiment”) will be describedin detail.

The present embodiment described below is only an example for describingthe present invention. The present invention will not be limited to theembodiment, and can be modified in various ways within the gist andimplemented.

[Polyamide Resin Composition]

The polyamide resin composition according to the present embodimentcomprises:

a polyamide resin (A),

a copper compound (B),

a bromide of an alkali metal and/or a bromide of an alkaline earth metal(C), and

at least one phosphorus compound (D) selected from the group consistingof phosphite compounds represented by the following general formula (1)and phosphonite compounds represented by the following general formula(2):

phosphite compound: (RO)_(m)P(OH)_(3-m)  general formula (1) and

phosphonite compound: (RO)_(n)P(OH)_(2-n)(R)  general formula (2)

wherein m represents 1, 2, or 3; n represents 1 or 2; R represents analiphatic group, an aromatic group, or a partially substituted aliphaticgroup or aromatic group; and if each of m and n is 2 or more, aplurality of (RO) groups in the general formulas (1) and (2) are thesame or different from each other.

Hereinafter, each component of the polyamide resin composition accordingto the present embodiment will be described in detail.

(Polyamide Resin (A))

The polyamide resin composition according to the present embodimentcontains a polyamide resin (A) (hereinafter, also referred to as acomponent (A)). The polyamide resin indicates a polymer having a —CO—NH—bond (amide bond) in the main chain.

Examples of the polyamide resin (A) include, but are not limited to, apolyamide resin obtained by the ring-opening polymerization of a lactam,a polyamide resin obtained by the self-condensation of aω-aminocarboxylic acid, a polyamide resin obtained by the condensationof a diamine and a dicarboxylic acid, and copolymers thereof.

These polyamide resins can be used singly, or can be used in combinationin the form of a mixture.

Hereinafter, the raw materials for the polyamide resin (A) will bedescribed.

Examples of the lactam as a monomer, which is a component of thepolyamide resin, include, but are not limited to, pyrrolidone,caprolactam, undecalactam, and dodecalactam.

Examples of the ω-aminocarboxylic acid include, but are not limited to,ω-amino fatty acids, which are ring-opened compounds of the lactams withwater. These lactams or ω-aminocarboxylic acids each can be used singlyor can be used in combination of two or more thereof.

Next, the polyamide resin obtained by the condensation of a diamine anda dicarboxylic acid will be described.

First, examples of the diamine (monomer) include, but are not limitedto, linear aliphatic diamines such as hexamethylenediamine andpentamethylenediamine; branched aliphatic diamines such as2-methylpentanediamine and 2-ethylhexamethylenediamine; aromaticdiamines such as p-phenylenediamine and m-phenylenediamine; andalicyclic diamines such as cyclohexanediamine, cyclopentanediamine, andcyclooctanediamine.

Examples of the dicarboxylic acid (monomer) include, but are not limitedto, aliphatic dicarboxylic acids such as adipic acid, pimelic acid, andsebacic acid; aromatic dicarboxylic acids such as phthalic acid andisophthalic acid; and alicyclic dicarboxylic acids such ascyclohexanedicarboxylic acid.

These diamines or dicarboxylic acids as a monomer each can be usedsingly or can be used in combination of two or more thereof.

Examples of the polyamide resin (A) include, but are not limited to,polyamide 4 (poly-α-pyrrolidone), polyamide 6 (polycaproamide),polyamide 11 (polyundecanamide), polyamide 12 (polydodecanamide),polyamide 46 (polytetramethylene adipamide), polyamide 66(polyhexamethylene adipamide), polyamide 610, polyamide 612, polyamide6T (polyhexamethylene terephthalamide), polyamide 9T (polynonamethyleneterephthalamide), and polyamide 6I (polyhexamethylene isophthalamide),and copolymerized polyamides containing these polyamides as a component.

These polyamide resins each can be used singly or can be used incombination of two or more thereof.

Among the polyamide resins listed above, more preferred are polyamideresins having a melting point of 200° C. or more to enhance the heatresistance.

Examples of the polyamide resin having a melting point of 200° C. ormore include, but are not limited to, at least one polyamide resinselected from the group consisting of polyamide 6, polyamide 66,polyamide 610, polyamide 612, polyamide 46, polyamide 6T, polyamide 6I,and polyamide 9T, and copolymerized polyamides containing thesepolyamides as a component.

The melting point of the polyamide resin indicates a melting pointdetermined by differential scanning calorimetry (DSC) in accordance withJIS K7121.

The ratio of the number of carbon atoms to the number of nitrogen atoms(ratio C/N) in the polymer chain of the polyamide resin (A) ispreferably more than 5 from the viewpoint of heat aging resistance. Theratio of the number of carbon atoms to the number of nitrogen atoms(ratio C/N) is more preferably more than 5 and 15 or less, morepreferably more than 5 and 12 or less.

Examples of the polyamide resin which is a copolymer include, but arenot limited to, at least one copolymer selected from the groupconsisting of a copolymer of hexamethylene adipamide and hexamethyleneterephthalamide, a copolymer of hexamethylene adipamide andhexamethylene isophthalamide, and a copolymer of hexamethyleneterephthalamide and 2-methylpentanediamine terephthalamide.

The polyamide resin (A) typically has an amino group or a carboxyl groupas terminal groups. The content ratio of the terminal groups in thepolyamide resin (A), i.e., content of amino group/content of carboxylgroup is preferably 9/1 to 1/9, more preferably 6/4 to 1/9, still morepreferably 5/5 to 1/9. A content ratio of the terminal groups withinthis range tends to be able to more significantly enhance the mechanicalstrength of the polyamide resin composition according to the presentembodiment.

The content of the terminal amino group in the polyamide resin (A) ispreferably 10 to 100 μmol/g, more preferably 15 to 80 μmol/g, still morepreferably 30 to 80 μmol/g. A content of the terminal amino group in thepolyamide resin (A) within this range tends to be able to moresignificantly enhance the mechanical strength of the polyamide resincomposition according to the present embodiment.

The content of the terminal carboxyl group in the polyamide resin (A) ispreferably 20 μmol/g or more, more preferably 50 μmol/g or more, furtherpreferably 50 to 120 μmol/g, still further preferably 50 to 100 μmol/g.

A content of the terminal carboxyl group in the polyamide resin (A)within this range tends to be able to more significantly enhance theheat aging resistance of the polyamide resin composition according tothe present embodiment.

Throughout the specification, the contents of the terminal amino groupand the terminal carboxyl group in the polyamide resin (A) can bedetermined from the integrated values of characteristic signalscorresponding to the respective terminal groups, which are obtained by¹H-NMR.

The contents of the terminal groups in the polyamide resin (A) can beadjusted by known methods. Examples of such methods of adjusting thecontents of the terminal groups include, but not limited to, a methodusing a terminal adjuster.

Specifically, the contents of the terminal groups in the polyamide resin(A) can be adjusted through addition of one or more compounds selectedfrom the group consisting of monoamine compounds, diamine compounds,monocarboxylic acid compounds, and dicarboxylic acid compounds duringpolymerization of the polyamide resin so as to attain predeterminedcontents of the terminal groups.

These compounds, if functioning as a terminal adjuster, can be added tothe polymerization solvent at any timing, for example, at a timing wherethe raw materials for the polyamide resin (A) are added to thepolymerization solvent.

Examples of the monoamine compounds include, but are not limited to,aliphatic monoamines such as methylamine, ethylamine, propylamine,butylamine, hexylamine, octylamine, decylamine, stearylamine,dimethylamine, diethylamine, dipropylamine, and dibutylamine; alicyclicmonoamines such as cyclohexylamine and dicyclohexylamine; aromaticmonoamines such as aniline, toluidine, diphenylamine, and naphthylamine;and any mixtures thereof.

These monoamine compounds each can be used singly or can be used incombination of two or more thereof.

Among these monoamine compounds, at least one compound selected from thegroup consisting of butylamine, hexylamine, octylamine, decylamine,stearylamine, cyclohexylamine, and aniline is particularly preferredfrom the viewpoint of reactivity, boiling point, stability of terminalgroups, and price, etc.

Examples of the diamine compounds include, but are not limited to,linear aliphatic diamines such as hexamethylenediamine andpentamethylenediamine; branched aliphatic diamines such as2-methylpentanediamine and 2-ethylhexamethylenediamine; aromaticdiamines such as p-phenylenediamine and m-phenylenediamine; andalicyclic diamines such as cyclohexanediamine, cyclopentanediamine, andcyclooctanediamine.

These diamine compounds each can be used singly or can be used incombination of two or more thereof.

Examples of the monocarboxylic acid compounds include, but are notlimited to, aliphatic monocarboxylic acids such as acetic acid,propionic acid, butyric acid, valeric acid, caproic acid, capric acid,lauric acid, tridecylic acid, myristic acid, palmitic acid, stearicacid, pivalic acid, and isobutyric acid; alicyclic monocarboxylic acidssuch as cyclohexanecarboxylic acid; and aromatic monocarboxylic acidssuch as benzoic acid, toluic acid, α-naphthalenecarboxylic acid,β-naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid, andphenylacetic acid.

These carboxylic acid compounds each can be used singly or can be usedin combination of two or more thereof.

Examples of the dicarboxylic acid compounds include, but are not limitedto, aliphatic dicarboxylic acids such as malonic acid, dimethylmalonicacid, succinic acid, glutaric acid, adipic acid, 2-methyladipic acid,trimethyladipic acid, pimelic acid, 2,2-dimethylglutaric acid,3,3-diethylsuccinic acid, azelaic acid, sebacic acid, and suberic acid;alicyclic dicarboxylic acids such as 1,3-cyclopentanedicarboxylic acidand 1,4-cyclohexanedicarboxylic acid; and aromatic dicarboxylic acidssuch as isophthalic acid, 2,6-naphthalenedicarboxylic acid,2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid,1,4-phenylenedioxydiacetic acid, 1,3-phenylenedioxydiacetic acid,diphenic acid, diphenylmethane-4,4′-dicarboxylic acid,diphenylsulfone-4,4′-dicarboxylic acid, and 4,4′-biphenyldicarboxylicacid.

These dicarboxylic acid compounds each can be used singly or can be usedin combination of two or more thereof.

The content of the polyamide resin (A) in the polyamide resincomposition according to the present embodiment is preferably 30 to99.94% by mass, more preferably 40 to 99.94% by mass, more preferably 40to 99.86% by mass, with respect to the total mass of the compositionfrom the viewpoint of enhancing the molding properties and themechanical strength.

(Copper Compound (B))

The polyamide resin composition according to the present embodimentcontains a copper compound (B) (hereinafter, also referred to as acomponent (B)).

Examples of the copper compound (B) include, but not limited to, copperhalides (such as copper iodide, cuprous bromide, cupric bromide, andcuprous chloride), copper acetate, copper propionate, copper benzoate,copper adipate, copper terephthalate, copper isophthalate, coppersalicylate, copper nicotinate, copper stearate, and copper complex saltshaving copper coordinated with a chelating agent such as ethylenediamineor ethylenediaminetetraacetic acid.

These copper compounds each can be used singly or can be used incombination of two or more thereof.

Among the copper compounds (B) listed above, at least one compoundselected from the group consisting of copper halides (such as copperiodide, cuprous bromide, cupric bromide, and cuprous chloride) andcopper acetate, more preferred are copper halides, and still morepreferred are copper iodide and/or cuprous bromide. Use of these coppercompounds tends to attain a polyamide resin composition which has highheat aging resistance and is less likely to cause corrosion of metal inscrews and cylinders during extrusion (hereinafter simply referred to as“corrosion of metal”).

The content of the copper compound (B) in the polyamide resincomposition according to the present embodiment is preferably 0.001 to0.2% by mass, more preferably 0.005 to 0.15% by mass, further preferably0.01 to 0.1% by mass, with respect to 100% by mass of the polyamideresin composition, i.e., the total mass of the polyamide resincomposition.

If the content of the copper compound (B) in the polyamide resincomposition falls within the range described above, the heat agingresistance tends to be able to be more significantly enhanced, anddeposition of copper and corrosion of metal tends to be able to beeffectively reduced.

The content of the copper element in the polyamide resin composition ispreferably 0.001% by mass or more, more preferably 0.005% by mass ormore, further preferably 0.005 to 0.05% by mass, still furtherpreferably 0.007 to 0.03% by mass, with respect to 100% by mass of thepolyamide resin composition, i.e., the total mass of the polyamide resincomposition, from the viewpoint of enhancing the heat aging resistanceof the polyamide resin composition.

(Bromide of Alkali Metal and/or Bromide of Alkaline Earth Metal (C))

The polyamide resin composition according to the present embodimentcontains bromide of alkali metal and/or Bromide of alkaline earth metal(C) (hereinafter, also referred to as a component (C)).

Examples of the bromide of alkali metal and/or Bromide of alkaline earthmetal (C) include, but are not limited to, potassium bromide, sodiumbromide, lithium bromide, calcium bromide, and magnesium bromide, andmixtures thereof.

In particular, the component (C) is preferably potassium bromide and/orsodium bromide, more preferably potassium bromide, from the viewpoint ofenhancing the heat aging resistance of the polyamide resin compositionaccording to the present embodiment and suppressing corrosion of metal.

The content of the bromide of alkali metal and/or bromide of alkalineearth metal (C) in the polyamide resin composition according to thepresent embodiment is preferably 0.05 to 5% by mass, more preferably 0.1to 2% by mass, further preferably 0.1 to 0.5% by mass, with respect to100% by mass of the polyamide resin composition, i.e., the total mass ofthe polyamide resin composition.

If the content of the bromide of alkali metal and/or bromide of alkalineearth metal (C) is within the range described above, the heat agingresistance of the polyamide resin composition tends to be able to bemore significantly enhanced, and deposition of copper and corrosion ofmetal tends to be able to be effectively reduced.

The copper compound (B) and the bromide of an alkali metal and/orbromide of an alkaline earth metal (C) are preferably contained in thepolyamide resin composition according to the present embodiment at amolar ratio of the halogen element to the copper element (halogenelement/copper element) of preferably 2/1 to 50/1, more preferably 5/1to 30/1, still more preferably 5/1 to 20/1.

If the content ratio (halogen element/copper element) is within thisrange, the heat aging resistance of the polyamide resin compositionaccording to the present embodiment tends to be able to be moresignificantly enhanced.

Throughout the specification, the halogen element indicates the total ofa halogen element derived from a copper halide, if the copper compound(B) is the copper halide, and a bromine element derived from the bromideof an alkali metal and/or bromide of an alkaline earth metal (C).

A molar ratio of the halogen element to the copper element (halogenelement/copper element) of 2/1 or more tends to reduce deposition ofcopper and corrosion of metal effectively in the polyamide resincomposition according to the present embodiment.

If the molar ratio (halogen element/copper element) is 50/1 or less,corrosion of screws and the like in molding machines tends to be able tobe prevented without essentially impairing mechanical properties, suchas toughness, of the polyamide resin composition according to thepresent embodiment.

(Phosphorus Compound (D))

The polyamide resin composition according to the present embodimentcontains a phosphorus compound (D) (hereinafter, also referred to as acomponent (D)).

The phosphorus compound (D) is at least one compound selected from thegroup consisting of phosphite compounds represented by the followinggeneral formula (1), and phosphonite compounds represented by thefollowing general formula (2):

phosphite compound: (RO)_(m)P(OH)_(3-m)  general formula (1) and

phosphonite compound: (RO)_(n)P(OH)_(2-n)(R)  general formula (2)

In the general formulas (1) and (2), m represents 1, 2, or 3, and nrepresents 1 or 2.

R represents an aliphatic group, an aromatic group, or a partiallysubstituted aliphatic group or aromatic group.

If each of m and n is 2 or more, a plurality of (RO) groups in thegeneral formulas (1) and (2) are the same or different from each other.

Examples of the group represented by R include, but are not limited to,aliphatic groups such as a methyl group, an ethyl group, a n-propylgroup, a n-butyl group, a t-butyl group, a n-hexyl group, a cyclohexylgroup, a n-octyl group, a nonyl group, a decyl group, a stearyl group,and an oleyl group; aromatic groups such as a phenyl group and abiphenyl group; and aliphatic groups or aromatic groups each having asubstituent such as a hydroxyl group, a methyl group, an ethyl group, apropyl group, a butyl group, a methoxy group, or an ethoxy group.

The phosphorus compound (D) can be at least one compound selected fromthe group consisting of phosphite compounds represented by the generalformula (1), and phosphonite compounds represented by the generalformula (2). Examples thereof include, but are not limited to,tris(2,4-di-t-butylphenyl)phosphite,bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite,bis(2,6-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite,bis(2,4-dicumylphenyl)pentaerythritol diphosphite,2,2′,2″-nitrilo(triethyl-tris(3,3′,5,5′-tetra-t-butyl-1,1′-biphenyl-2,2′-diyl))phosphite,tetrakis(2,4-di-t-butylphenyl)-4,4′-biphenylene diphosphonite,tetrakis(2,4-di-t-butylphenyl)-4,3′-biphenylene diphosphonite,tetrakis(2,4-di-t-butylphenyl)-3,3′-biphenylene diphosphonate.

These phosphorus compounds (D) each can be used singly or can be used asa mixture of two or more thereof.

The content of the phosphorus compound (D) is preferably 0.01 to 10% bymass, more preferably 0.01 to 5% by mass, further preferably 0.03 to 2%by mass, with respect to 100% by mass of the polyamide resin compositionaccording to the present embodiment, i.e., the total mass of thepolyamide resin composition.

Within the range described above, there is a tendency to yield apolyamide resin composition that is much superior in the suppression ofcorrosion of metal and copper deposition.

The bromide of alkali metal and/or bromide of alkaline earth metal (C)[x] and the phosphorus compound (D) [y] are preferably contained in thepolyamide resin composition according to the present embodiment suchthat the mass ratio [x/y] of the bromide of alkali metal and/or bromideof alkaline earth metal (C) to the phosphorus compound (D) (component(C)/component (D)) in the polyamide resin composition is 100/1 to 1/100,more preferably 50/1 to 1/50, further preferably 10/1 to 1/10, stillfurther preferably 10/1 to 1/1.

If mass ratio of the component (C)/component (D) is within the rangedescribed above, there is a tendency to be able to further enhance theheat aging resistance of the polyamide resin composition according tothe present embodiment and also to further suppress corrosion of metaland copper deposition.

(Other Components that can be Contained in Polyamide Resin Composition)

(Fatty Acid Compound (E))

The polyamide resin composition according to the present embodiment canfurther contain at least one fatty acid compound (E) selected from thegroup consisting of fatty acid esters, fatty acid amides, and fatty acidmetal salts (hereinafter, also referred to as a fatty acid compound (E)or a component (E)) from the viewpoint of further enhancing heat agingresistance.

These fatty acid compounds each can be used singly or can be used incombination of two or more thereof.

The fatty acid constituting the fatty acid compound (E) indicates analiphatic monocarboxylic acid.

Particularly, a fatty acid having 8 or more carbon atoms is preferred. Afatty acid having 8 to 40 carbon atoms is more preferred. Examples ofthe fatty acid include, but are not limited to, saturated or unsaturatedlinear or branched aliphatic monocarboxylic acids.

Examples of the fatty acid include, but are not limited to, stearicacid, palmitic acid, behenic acid, erucic acid, oleic acid, lauric acid,and montanic acid.

The fatty acid esters are ester compounds of the aforementioned fattyacid and an alcohol.

Examples of the alcohol include, but are not limited to, 1,3-butanediol,trimethylolpropane, stearyl alcohol, behenyl alcohol, and laurylalcohol.

Examples of the fatty acid esters include, but are not limited to,stearyl stearate, behenyl behenate, montanic acid-1,3-butanediol ester,montanic acid-trimethylolpropane ester, trimethylolpropane trilaurate,and butyl stearate.

The fatty acid amides are amidated products of the aforementioned fattyacid.

Examples of the fatty acid amides include, but are not limited to,stearic acid amide, oleic acid amide, erucic acid amide, ethylenebisstearamide, ethylene bisoleamide, N-stearyl stearamide, and N-stearylerucamide. Among these fatty acid amides, particularly, stearic acidamide, erucic acid amide, ethylene bisstearamide, and N-stearylerucamide are preferred, and ethylene bis(stearamide) and N-stearylerucamide are more preferred.

The fatty acid metal salts are metal salts of the aforementioned fattyacid.

Examples of the metal element that forms a salt with the fatty acidinclude group 1 elements (alkali metals) of the periodic table, group 2elements (alkaline earth metals) of the periodic table, group 3 elementsof the periodic table, zinc, and aluminum.

The metal element is preferably an alkali metal such as sodium andpotassium; an alkaline earth metal such as calcium and magnesium; oraluminum.

Examples of the fatty acid metal salts include, but are not limited to,higher fatty acid metal salts such as calcium stearate, aluminumstearate, zinc stearate, magnesium stearate, calcium montanate, sodiummontanate, aluminum montanate, zinc montanate, magnesium montanate,calcium behenate, sodium behenate, zinc behenate, calcium laurate, zinclaurate, and calcium palmitate.

Throughout the specification, the higher fatty acid is a fatty acidhaving more than 10 carbon atoms.

Among these fatty acid metal salts, a montanic acid metal salt, abehenic acid metal salt, and a stearic acid metal salt are preferablyused. Particularly, calcium stearate, aluminum stearate, zinc stearate,magnesium stearate, calcium montanate, zinc montanate, magnesiummontanate, calcium behenate, and zinc behenate are preferred. Aluminumstearate, zinc stearate, magnesium stearate, calcium montanate, zincmontanate, calcium behenate, and zinc behenate are more preferred.Calcium montanate, zinc montanate, and zinc behenate are furtherpreferred.

These fatty acid metal salts each can be used singly or can be used incombination of two or more thereof.

If the fatty acid compound (E) is a fatty acid metal salt, this fattyacid metal salt is preferably a higher fatty acid metal salt with ametal content of 3.5 to 11.5% by mass. As a result, there is a tendencyto yield a polyamide resin composition that is much superior in thesuppression of corrosion of metal and copper deposition, appearance, andmold release properties. The metal content is more preferably 3.5 to10.0% by mass, further preferably 4.0 to 9.0% by mass.

The fatty acid compound (E) preferably has an acid value determined inaccordance with JIS K 0070 (the number of milligrams of potassiumhydroxide needed to neutralize free fatty acids, resin acids etc., in asample (1 g)) of 10 mg/g or less from the viewpoint of suppressingcorrosion of metal and copper deposition by the polyamide resincomposition according to the present embodiment. The acid value is morepreferably 0.01 to 10 mg/g, further preferably 0.01 to 5 mg/g, stillfurther preferably 0.01 to 3 mg/g, particularly preferably 0.01 to 1mg/g.

The fatty acid compound (E) is preferably a fatty acid amide or a fattyacid metal salt from the viewpoint of further enhancing moldability andis more preferably a fatty acid metal salt, particularly, from theviewpoint of still further attaining a better appearance and higher moldrelease properties of the polyamide resin composition according to thepresent embodiment.

The melting point of the fatty acid compound (E) is preferably 110 to150° C., more preferably 115 to 145° C., further preferably 115 to 140°C., from the viewpoint of still further attaining a better appearanceand higher mold release properties of the polyamide resin compositionaccording to the present embodiment.

The melting point of the fatty acid compound (E) can be determined bydifferential scanning calorimetry (DSC) or the like.

The content of the fatty acid compound (E) is preferably 0.01 to 10% bymass, more preferably 0.03 to 5% by mass, further preferably 0.05 to 2%by mass, with respect to 100% by mass of the polyamide resin compositionaccording to the present embodiment, i.e., the total mass of thepolyamide resin composition.

If the content of the fatty acid compound (E) is within the rangedescribed above, there is a tendency to yield a polyamide resincomposition that is much superior in a better appearance, higher moldrelease properties, higher mechanical strength, and higher plasticity.

The ratio between the bromide of alkali metal and/or bromide of alkalineearth metal (C) and the fatty acid compound (E) contained in thepolyamide resin composition according to the present embodiment ispreferably 2/1 to 1/10, more preferably 2/1 to 1/5, further preferably1/1 to 1/5, still further preferably 1/1 to 1/3, in terms of mass ratioof component (C)/component (E).

If the mass ratio of component (C)/component (E) is within the rangedescribed above, there is a tendency to be able to further enhance theheat aging resistance of the polyamide resin composition according tothe present embodiment and also to still further suppress corrosion ofmetal and copper deposition.

(Inorganic Filler (F))

The polyamide resin composition according to the present embodiment canfurther contain an inorganic filler (F) (hereinafter, also referred toas a component (F)) in addition to the aforementioned components (A) to(D) and the component (E).

Examples of the inorganic filler (F) include, but are not limited to,glass fibers, carbon fibers, calcium silicate fibers, potassium titanatefibers, aluminum borate fibers, glass flakes, talc, kaolin, mica,hydrotalcite, calcium carbonate, zinc carbonate, zinc oxide, calciummonohydrogen phosphate, wollastonite, silica, zeolite, alumina,boehmite, aluminum hydroxide, titanium oxide, silicon oxide, magnesiumoxide, calcium silicate, sodium aluminosilicate, magnesium silicate,ketjen black, acetylene black, farness black, carbon nanotubes,graphite, yellow copper, copper, silver, aluminum, nickel, iron, calciumfluoride, mica, montmorillonite, swellable fluorine mica, and apatite.

These inorganic fillers each can be used singly or can be used incombination of two or more thereof.

Among those mentioned above, at least one inorganic filler (F) selectedfrom the group consisting of glass fibers, carbon fibers, glass flakes,talc, kaolin, mica, wollastonite, silica, carbon nanotubes, graphite,calcium fluoride, montmorillonite, swellable fluorine mica, and apatiteis preferred from the viewpoint of enhancing the mechanical strength andrigidity of the polyamide resin composition according to the presentembodiment.

The inorganic filler (F) is more preferably at least one inorganicfiller selected from the group consisting of glass fibers, carbonfibers, wollastonite, talc, mica, kaolin, and silicon nitride.

The glass fibers and the carbon fibers in the polyamide resincomposition preferably have a number average fiber diameter of 3 μm to30 μm, a weight average fiber length of 100 μm to 750 μm, and an aspectratio of the weight average fiber length to the number average fiberdiameter (value obtained by dividing the weight average fiber length bythe number average fiber diameter) of 10 to 100 to attain a polyamideresin composition having high mechanical properties.

The wollastonite in the polyamide resin composition preferably have anumber average fiber diameter of 3 μm to 30 μm, a weight average fiberlength of 10 μm to 500 μm, and an aspect ratio of 3 to 100 to attain apolyamide resin composition having high mechanical properties.

The talc, mica, kaolin, and silicon nitride in the polyamide resincomposition preferably have a number average particle diameter of 0.1 μmto 3 μm to attain a polyamide resin composition having high mechanicalproperties.

Throughout the specification, the number average fiber diameter, thenumber average particle diameter, and the weight average fiber lengthcan be determined by the following methods.

A polyamide resin composition is placed in an electric furnace to burnorganic substances contained in the resin composition. For example, morethan 100 inorganic fillers are arbitrarily selected from the residue,and are observed with a scanning electron microscope (SEM) to determinethe fiber diameters and the particle diameters of these inorganicfillers, and in turn the number average fiber diameter and the numberaverage particle diameter. The fiber lengths are measured with an SEMphotograph at a magnification of 1000 times to determine the weightaverage fiber length.

The inorganic filler (F) may be subjected to a surface treatment with asilane coupling agent.

Examples of the silane coupling agent include, but not limited to,aminosilanes such as γ-aminopropyltriethoxysilane,γ-aminopropyltrimethoxysilane andN-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane; mercaptosilanessuch as γ-mercaptopropyltrimethoxysilane andγ-mercaptopropyltriethoxysilane; expoxysilanes; and vinylsilanes.

The inorganic filler is preferably one or more inorganic fillersselected from the group above. More preferred are aminosilanes.

The glass fibers and the carbon fibers may further contain a sizingagent such as copolymers containing a carboxylic anhydride-containingunsaturated vinyl monomer and an unsaturated vinyl monomer excluding thecarboxylic anhydride-containing unsaturated vinyl monomer as structuralunits, epoxy compounds, polycarbodiimide compounds, polyurethane resins,homopolymers of acrylic acid, copolymers of acrylic acid and othercopolymerizable monomers, and salts of primary, secondary, and tertiaryamines thereof. These can be used singly or in combinations of two ormore thereof.

The glass fibers or the carbon fibers can be obtained, for example, bycontinuous reaction using the aforementioned sizing agent in a glassfiber or carbon fiber production process known in the art.

Specifically, the sizing agent is applied to glass fibers or carbonfibers using a method known in the art such as a roller-type applicator,and the fiber strand thus produced can be dried to obtain the glassfibers or the carbon fibers mentioned above.

The fiber strand may be used directly as a roving or nay be used as achopped glass strand through a further cutting step.

The sizing agent is applied (added) to the glass or carbon fibers (100%by mass) in a solid content of preferably 0.2 to 3% by mass, morepreferably 0.3 to 2% by mass.

The solid content in the sizing agent to be added is preferably 0.2% bymass or more based on 100% by mass of the glass or carbon fibers tomaintain sizing of the glass or carbon fibers. The amount of the sizingagent to be added in terms of the solid content is preferably 3% by massor less to enhance the thermal stability of the polyamide resincomposition according to the present embodiment. The strands may bedried after the cutting step, or may be cut after drying the strands.

In the case of using the inorganic filler (F) in the polyamide resincomposition according to the present embodiment, the content of theinorganic filler (F) in the polyamide resin composition is preferably 10to 70% by mass, more preferably 15 to 65% by mass, further preferably 20to 65% by mass, from the viewpoint of enhancing moldability andmechanical strength.

(Additional Component)

The polyamide resin composition according to the present embodiment mayfurther contain an additional component, if necessary, without impairingthe effects of the present invention, in addition to the aforementionedcomponents (A) to (F).

Examples of the additional component that can be added to the polyamideresin composition include, but are not limited to, secondary aminecompounds, antioxidants, ultraviolet absorbers, heat stabilizers, lightdegradation inhibitors, plasticizers, lubricants, mold release agents,nucleating agents, flame retardants, colorants, dyeing agents, andpigments. Alternatively, other thermoplastic resins can be mixedtherewith.

Examples of the secondary amine compounds include, but are not limitedto, aromatic secondary amine compounds and hindered amine lightstabilizers (HALS). Particularly, an aromatic secondary amine compoundis preferred from the viewpoint of the suppression of metal corrosiveproperties and the mechanical strength of the polyamide resincomposition.

These additional components largely differ in their properties.Therefore, their preferred contents that hardly impair the effectsaccording to the present embodiment vary among these components. Thoseskilled in the art can readily set the respective preferred contents ofthese additional components.

[Method for Producing Polyamide Resin Composition]

The method for preparing the polyamide resin composition according tothe present embodiment can be, but is not limited to, a method ofmelting the polyamide resin (A) in a mono- or multi-axial extruder, andkneading the component (B), the component (C), and the component (D)with the melted polyamide resin (A).

If the inorganic filler (F) is used, a twin screw extruder provided withan upstream feeding port and a downstream feeding port is preferablyused to feed the inorganic filler (F) from the downstream feeding portfor melt kneading after feeding the polyamide resin (A), the component(B), the component (C), and the component (D) and optionally, thecomponent (E) from the upstream feeding port and melting. If a roving ofglass or carbon fibers is used, a composite product can be prepared by aknown method.

[Characteristics of Polyamide Resin Composition]

Preferably, the polyamide resin composition according to the presentembodiment does not cause the deposition of the copper element on thesurface of a rolled steel (SS400) if the polyamide resin composition isin contact with the rolled steel for 12 hours at a temperature of 30° C.plus the melting point of the polyamide resin (A).

The polyamide resin composition according to the present embodimentcontaining the phosphorus compound (D) tends to be able to effectivelysuppress copper deposition. The polyamide resin composition according tothe present embodiment containing the fatty acid compound (E) having anacid value of 10 mg/g or less tends to be able to more effectivelysuppress copper deposition.

The copper deposition of the polyamide resin composition according tothe present embodiment can be tested by a method described in Examplesmentioned later.

The molded article according to the present embodiment comprises theaforementioned polyamide resin composition according to the presentembodiment and can be produced, for example, by the injection molding ofthe polyamide resin composition.

[Applications]

The molded article according to the present embodiment can be suitablyused as various molded articles and parts, for example, for vehicles,industrial machines, electric and electronic apparatuses and devices,trade and industrial materials, and daily household goods.

EXAMPLES

Hereinafter, the present invention will be described in detail withreference to specific Examples and Comparative Examples. However, thepresent invention is not intended to be limited by these Examples.

[Methods for Evaluation]

Hereinafter, methods for evaluation conducted in Examples andComparative Examples will be described.

<Tensile Strength>

Pellets of the polyamide resin compositions prepared in Examples andComparative Examples were molded into multi-purpose test pieces (A type)with an injection molding machine (PS-40E: made by NISSEI PLASTICINDUSTRIAL CO., LTD.) by a method in accordance with ISO 3167.

In molding, the time for injection and hold-pressure was set at 25seconds, the cooling time at 15 seconds, the mold temperature at 80° C.,and a melt resin temperature at 290° C.

The prepared multi-purpose test pieces (A type) were subjected to atensile test at a tensile rate of 5 mm/min by a method in accordancewith ISO 527 to determine the tensile strength (MPa).

<Tensile Strength after Heat Aging>

The multi-purpose test pieces (A type) prepared in the evaluation oftensile strength above were thermally aged in a hot air circulating ovenat 150° C. for 2,000 hours.

These test pieces were cooled at 23° C. for 24 hours, and were subjectedto a tensile test at a tensile rate of 5 mm/min by a method inaccordance with ISO 527 to determine the tensile strength (MPa) afterheat aging for 2,000 hours.

<Corrosion of Metal>

20 g of pellets of the polyamide resin compositions prepared in Examplesand Comparative Examples were each placed in an autoclave made of SUS314and having pressure resistance to 2.0 MPa and an inner volume of 100 mL.A rolled steel (SS400) test piece (10 mm×20 mm×2 mm) having a surfacepolished with a #2000 whetstone were then added, and additional pellets(20 g) of the polyamide resin composition were deposited over the rolledsteel test piece.

The autoclave was purged with nitrogen, and was hermetically sealed. Thepolyamide resin compositions were heated at 290° C. for 12 hours.

The autoclave was then cooled under running water to room temperature,and was opened.

The rolled steel test piece was extracted from the melt and solidifiedpellets of the polyamide resin compositions. The polyamide resincomposition adhering to the surface of the rolled steel test piece wasremoved with hexafluoropropanol (HFIP). The mass of the rolled steeltest piece was precisely weighed in order of 0.01 mg, and was divided bythe predetermined mass of the rolled steel test piece before the test todetermine the mass reduction rate in mass ppm.

<Copper Deposition>

The surface of the rolled steel test specimen was observed after theaforementioned corrosion of metal test, and the deposition status of thecopper element was visually observed and evaluated as follows:

A: No deposition of the copper element was observed.

B: The deposition of the copper element was less than 5% of the surfacearea of the rolled steel.

C: The deposition of the copper element was 5% or more and less than 10%of the surface area of the rolled steel.

D: The deposition of the copper element was 10% or more of the surfacearea of the rolled steel.

[Preparation of Raw Material] (1. Polyamide Resin) (1-1) Polyamide 66(Hereinafter, Referred to as “PA-1”)

VN (sulfuric acid): 143 mL/g,

Terminal amino group: 48 mmol/kg,

Terminal carboxylic acid group: 79 mmol/kg,

Melting point: 260° C.

(1-2) Polyamide 66 (Hereinafter, Referred to as “PA-2”)

VN (sulfuric acid): 140 mL/g,

Terminal amino group: 80 mmol/kg,

Terminal carboxylic acid group: 46 mmol/kg,

Melting point: 260° C.

(2. Copper Iodide (Hereinafter, Referred to as “CuI”))

A reagent manufactured by Wako Pure Chemical Industries, Ltd. was used.

(3. Potassium Bromide (Hereinafter, Referred to as “KBr”))

A reagent manufactured by Wako Pure Chemical Industries, Ltd. was used.

(4. Potassium Iodide (Hereinafter, Referred to as “KI”))

A reagent manufactured by Wako Pure Chemical Industries, Ltd. was used.

(5. Phosphorus Compound)

(5-1) Bis(2,6-Di-t-Butyl-4-Methylphenyl)Pentaerythritol DiphosphitePEP-36 (Hereinafter, Referred to as “PEP-36”), which is

A product manufactured by ADEKA Corp. was used.

(5-2) Tetrakis(2,4-Di-t-Butylphenyl)-4,4′-Biphenylene DiphosphoniteP-EPQ (Hereinafter, Referred to as “P-EPQ”)

A product manufactured by Clariant (Japan) K.K. was used.

(6. Fatty Acid Compound) (6-1) Calcium Montanate (Hereinafter, Referredto as “MonCa”)

Acid value: 0.8 mg/g, Melting point: 120° C.

(6-2) Ethylene Bis(Stearamide) (Hereinafter, Referred to as “EBS”)

Acid value: 8 mg/g, Melting point: 140° C.

(6-3) Zinc Stearate (Hereinafter, Referred to as “StZn”)

Acid value: 0.5 mg/g, Melting point: 120° C.

(6-4) Aluminum Monostearate (Hereinafter, Referred to as “StAl”)

Acid value: 14 mg/g, Melting point: 170° C.

(7. Inorganic Filler (Glass Fibers: Hereinafter, Referred to as “GF”))

Trade name: ECS 03T-275H (manufactured by Nippon Electric Glass Co.,Ltd.)

[Examples 1 to 12] and [Comparative Examples 1 to 5]

The extruder used was a twin-screw extruder [ZSK-26MC; manufactured byCoperion GmbH (Germany)] having an upstream feed port in the firstbarrel on the upstream side and a downstream feed port in the 9thbarrel, and having L/D (Length of the cylinder of the extruder/Diameterof the cylinder of the extruder) of 48 (the number of barrels: 12).

In this twin-screw extruder, the temperature from the upstream feed portto the die was set to 280° C., the number of screw revolutions was setto 250 rpm, and the discharge rate was set to 25 kg/hr.

Under these conditions, the polyamide resin (PA), CuI, KBr or KI, thephosphorus compound, and the fatty acid compound were supplied from theupstream feed port, while GF was supplied from the downstream feed portas to Examples 10 and 11 so as to attain the ratios described in theupper boxes of Tables 1 to 3 below.

The mixture was melt-kneaded to produce pellets of a polyamide resincomposition.

The obtained polyamide resin composition was molded at theaforementioned melted resin temperature and mold temperature, and themolded piece was evaluated for tensile strength, tensile strength afterheat aging, corrosion of metal, and copper deposition.

These evaluation (measurement) results, etc., are shown in Tables 1 to 3below.

TABLE 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example 6<Composition> (A) Polyamide resin PA-1 part by mass 99.2 99.05 98.3 98.399.05 PA-2 part by mass 98.3 (B) Copper iodide CuI part by mass 0.030.05 0.1 0.1 0.1 0.05 (C) Potassium bromide KBr part by mass 0.17 0.30.6 0.6 0.6 0.3 Potassium iodide KI part by mass (D) Phosphorus compoundPEP-36 part by mass 0.1 0.1 0.2 0.2 0.2 P-EPQ part by mass 0.1 (E) Fattyacid compound MonCa part by mass 0.8 EBS part by mass 0.5 0.5 0.5 StZnpart by mass 0.8 0.8 StAl part by mass (F) Inorganic filler GF part bymass <Physical properties> Tensile strength MPa 86 85 86 86 86 85Tensile strength after heat aging MPa 84 82 85 85 85 83 Metal corrosiveproperty Rate of decrease ppm 68 80 46 50 51 80 in mass Copperdeposition — B B A A A B

TABLE 2 Example 7 Example 8 Example 9 Example 10 Example 11 Example 12<Composition> (A) Polyamide resin PA-1 part by mass 98.3 98.3 98.3 98.364.05 64.05 PA-2 part by mass (B) Copper iodide CuI part by mass 0.1 0.10.1 0.1 0.05 0.05 (C) Potassium bromide KBr part by mass 0.6 0.6 0.6 0.60.3 0.3 Potassium iodide KI part by mass (D) Phosphorus PEP-36 part bymass 0.1 0.2 0.1 compound P-EPQ part by mass 0.2 0.2 0.1 0.1 (E) Fattyacid compound MonCa part by mass 0.8 0.8 0.5 EBS part by mass StZn partby mass 0.8 0.5 StAI part by mass 0.8 (F) Inorganic filler GF part bymass 35 35 <Physical properties> Tensile strength MPa 86 86 86 85 210208 Tensile strength after heat aging MPa 85 85 86 82 210 208 Metalcorrosive property Rate of decrease ppm 52 50 45 89 62 65 in mass Copperdeposition — A A A C A A

TABLE 3 Comparative Comparative Comparative Comparative ComparativeExample 1 Example 2 Example 3 Example 4 Example 5 <Composition> (A)Polyamide resin PA-1 part by mass 99.65 99.15 98.3 99.15 99.15 PA-2 partby mass (B) Copper iodide CuI part by mass 0.05 0.05 0.1 0.05 0.05 (C)Potassium bromide KBr part by mass 0.3 0.3 0.6 Potassium iodide KI partby mass 0.3 0.3 (D) Phosphorus compound PEP-36 part by mass 0.1 P-EPQpart by mass (E) Fatty acid compound MonCa part by mass EBS part by mass0.5 0.5 0.5 StZn part by mass 0.8 StAl part by mass (F) Inorganic fillerGF part by mass <Physical properties> Tensile strength MPa 82 84 84 8584 Tensile strength after heat aging MPa 65 80 81 72 71 Metal corrosiveproperty Rate of decrease ppm 130 201 143 65 66 in mass Copperdeposition — C D D A A

First, how to see Tables 1 to 3 will be described.

Higher tensile strength indicates better mechanical strength.

Higher tensile strength after heat aging indicates particularly betterheat aging resistance.

A smaller rate of decrease in mass in the corrosion of metal testindicates that metal corrosive properties are more effectivelysuppressed.

As shown in Table 1, in Examples 1 to 12, a polyamide resin compositionhaving high heat aging resistance, well-balanced and excellentsuppression of corrosion of metal and copper deposition, and favorableheat stability was obtained by use of the phosphorus compound.

Particularly, Examples 1 to 9, 11, and 12 supplemented with the fattyacid compound having an acid value of 10 mg/g or less further suppressedmetal corrosive properties and copper deposition and were thus foundfavorable.

On the other hand, Comparative Example 1 free from the phosphoruscompound and the fatty acid compound was shown to be inferior in heataging resistance.

Comparative Examples 2 and 3 containing the fatty acid compound but freefrom the phosphorus compound were shown to be inferior in metalcorrosive properties or copper-depositing properties, though heat agingresistance was excellent.

The comparison of Example 2 with Comparative Example 2, ComparativeExample 4, and Comparative Example 5 demonstrated that metal corrosiveproperties or copper-depositing properties are not influenced by theaddition of the phosphorus compound in the case of using potassiumiodide without the use of potassium bromide, whereas metal corrosiveproperties and copper-depositing properties can be effectivelysuppressed by the addition of the phosphorus compound in the case ofusing potassium bromide.

These results demonstrated that the polyamide resin composition of thepresent invention is high heat aging resistance and can effectivelysuppress corrosion of metal and copper deposition.

INDUSTRIAL APPLICABILITY

The polyamide resin composition of the present invention is industriallyapplicable as a material for molded products required to have highlevels of mechanical physical properties, such as vehicle parts andvarious electronic parts.

1. A polyamide resin composition comprising a polyamide resin (A), acopper compound (B), a bromide of an alkali metal and/or a bromide of analkaline earth metal (C), and at least one phosphorus (D) compoundselected from the group consisting of phosphite compounds represented bythe following formula (1), and phosphonite compounds represented by thefollowing formula (2):phosphite compound: (RO)_(m)P(OH)_(3-m)  formula (1) andphosphonite compound: (RO)_(n)P(OH)_(2-n)R)  formula (2) wherein mrepresents 1, 2, or 3; n represents 1 or 2; R represents an aliphaticgroup, an aromatic group, or a partially substituted aliphatic group oraromatic group; and if each of m and n is 2 or more, a plurality of (RO)groups in the general formulas (1) and (2) are the same or differentfrom each other.
 2. The polyamide resin composition according to claim1, wherein the copper compound (B) is a copper halide compound.
 3. Thepolyamide resin composition according to claim 1, wherein a molar ratioof a halogen element/a copper element in the polyamide resin compositionis 2/1 to 50/1.
 4. The polyamide resin composition according to claim 1,further comprising at least one fatty acid compound (E) selected fromthe group consisting of fatty acid esters, fatty acid amides, and fattyacid metal salts.
 5. The polyamide resin composition according to claim4, wherein the fatty acid compound (E) has an acid value of 10 mg/g orless.
 6. The polyamide resin composition according to claim 4, whereinthe fatty acid compound (E) is a higher fatty acid metal salt with ametal content of 3.5 to 11.5% by mass.
 7. The polyamide resincomposition according to claim 1, wherein the content of the copperelement in the polyamide resin composition is 0.005% by mass or morewith respect to the total mass of the polyamide resin composition. 8.The polyamide resin composition according to claim 1, wherein the massratio [x/y] of the bromide of alkali metal and/or bromide of alkalineearth metal (C) [x] to the phosphorus compound (D) [y] contained in thepolyamide resin composition is 100/1 to 1/100.
 9. The polyamide resincomposition according to claim 1, further comprising an inorganic filler(F).
 10. The polyamide resin composition according to claim 1, whereinthe polyamide resin composition does not cause the deposition of thecopper element on the surface of a rolled steel (SS400) after thepolyamide resin composition is in contact with the rolled steel at atemperature 30° C. higher than the melting point of the polyamide resin(A) for 12 hours.
 11. A molded article comprising a polyamide resincomposition according to claim
 1. 12. The molded article according toclaim 11, wherein the molded article is a vehicle part.